quicksort: add testing for complexity

Author: Laz4rz

quicksort.py

@@ -1,23 +1,35 @@
+import random 
+
+random.seed(42)
+
+def random_array(length, bottom, top):
+ return [random.randint(bottom, top) for i in range(length)]
+
 arr = [8, 2, 4, 7, 1, 3, 9, 6, 5]
 #arr = [64, 34, 25, 12, 22, 11, 90, 110]
 
 recursion_depth = 0
+n_operations = 0
 
 def quicksort(arr, start, end):
  """
  just by last element
  """
  original = arr[:] # for shallow copy
  if start >= end:
- assert all([el in original for el in arr]), "dang we lost someone"
+ # assert on sorting invariant:
+ # all elements have to match before and after, only position changes
+ assert set(original) == set(arr), "dang we lost someone"
  return arr
  pivot = arr[end]
  n = end
  i = start - 1
  swap = 0
 
+ global n_operations
  global recursion_depth
  recursion_depth += 1
+
  print(10*"=", f" Quicksort: {recursion_depth} ", 10*"=")
  print(f"{start=}, {end=}")
  print(arr)
@@ -30,6 +42,7 @@ def quicksort(arr, start, end):
  swap = arr[j]
  arr[j] = arr[i]
  arr[i] = swap
+ n_operations += 1
  arr[end] = arr[i+1]
  arr[i+1] = pivot
 
@@ -40,5 +53,11 @@ def quicksort(arr, start, end):
 arr = quicksort(arr, 0, len(arr)-1)
 
 print(f"\nFinal {arr}")
+print(f"Total number of operations: {n_operations}")
 
-
+# testing suite
+recursion_depth = 0
+n_operations = 0 
+for i in range(100):
+ quicksort(random_array(100, 0, 100), 0, 99)
+print(f"Average number of operations: {n_operations/100}")